CA1076808A - Production of a fuel gas and synthetic natural gas from methanol - Google Patents

Abstract

Abstract of the Disclosure Methanol is passed over a catalyst at an elevated temperature and pressure to produce a fuel gas containing a high proportion of methane in a one-step catalytic conversion process. Removal of water and carbon dioxide from the fuel gas produces a synthetic natural gas. For example, methanol with water is passed over a precious metal catalyst such as ruthenium on alumina at a temper-ature in the range of about 350°C to 500°C and a pressure in the range of about 800 to 2500 psig to produce a gaseous mixture comprising methane, carbon dioxide, minor amounts of hydrogen and essentially no carbon monoxide. Upon condensing the water vapor and scrubbing out the carbon dioxide, synthetic natural gas is obtained having a methane content above 90% by volume.

Description

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BACKGROUND OF THE INVENTION

This invention relates to a process for the production

2 of a f~el gas and more particularly to the single-step catalytic

3 ¦ conversion of a methanol feedstock to synthetlc natural gas.
~ ¦ Natural gas produced ~rom oil wells located remotely from 5 ¦ the ultimate user of the energy source was for many years burned or used at the site. With the developing shortage of fuel, ' 7 attempts have been made to liquify the natural gas and to ship 8 ¦ it in-refrigerated tankers to the ult~mate userO Such "flared 9 gas" is however expensive to liquify and ship. It has been suggested that this gas might be more economically used by first 11l converting it to methanol. The technology for doing this 12 presently exlsts by reforming natural gas~ primarily methane, ¦' 13 ¦ with steam to form a synthetic gas, which may be carried out over 14 ¦ a nickel catalyst. The resultant synthesls gas can be converted 15 ¦ over catalysts such as zinc oxide-chromlum oxide to produce 16 ~ methanol~ The crude methanol can then be transported in con-}7 ventional tankers to remote sources where it can be direc~ly 18 used for many purposes.
19 ¦ In addition, the growing shortage of o~l and natural 20 I gas has placed greater importance on coal as a fuel source.
21 ¦ However the direct use of coal presents ~any problems to its use 22 ¦ as a fuel source. Therefore it is desirable to convert coal to 23 ¦ other forms of fuelS whlch àre more compatible with present day 24 ¦ fuel consumlption devices, which can be more easily handled, and which lead to fewer adverse ecologlcal consequences. Coal can 26 be sub~ected to partial ox~dation in the presence of steam to 27 produce a synthetic gas which can then be converted to methanol.
28 One proposed method for util~zation of the methanol 29 obtained from natural gas or coal is to reform it to produce 3o synthet'ic natural gas. A conventional method for reformlng ~ -2-~
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1 ¦ the methanol is to do so at pressures of from about 100 to 300 2 ¦ psig to produce a product gas containing steam~ methane 9 3 ~ hydrogen, carbon monoxide and carbon dioxide. This product is

4 ¦ then subject to reaction over a methanation catalyAt to produce

5 I a synthetic natural gas consisting primarily of methane with a

6 ¦ minor amount of hydrogen. This prior art two-step conversion

7 ¦ can be represented as follows:

8 CH30H --:9 (a)CH4 + (b)H2 ~ (c)C0 ~ (d)C02 + (e)H~0

9 3H2 + CO ~,CH4 + H20 ~nother proposed method for making synthetic natural 11 gas is to steam reform naphtha. The naphtha and steam are 12 passed over a nickel containing catalyst bed to produce a 1 mixture of methane (about 25~-by volume)~ carbon monoxide, 14 carbon dioxide and hydrogen. Thereafter, one or two steps of 15 ¦ catalytic methanation are required to produce a synthetic 16 ¦ natural gas having a higher percentage of methane.
17 Indeed, an extensive amount of literature exists on 18 the production of methane from naphtha and other petroleum 19 hydrocarbons. In general, the naphtha is con~erted at a high temperature over a nickel catalyst to a methane-rich gas 21 which is then (after several optional intermediate steps) 22 passed over a methanation catalyst at a lower temperature 23 to bring about the formation of further amounts o~ methane 24 by reaction between carbon dioxide, carbon monoxide and hydrogen present in the gas. The process may comprise 26 passing a mixture of preheated hydrocarbons in vapor form 27 and ~team at atmospheric or superatmospheric pressure 28 through a bed of a nickel catalyst such that the bed 29 is maintained at temperatures in abo-lt the range l~50C to 750C. The resultant gases contain steam, hydrogen~ carbon `'~i . ' . I
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1 dioxide, carbon monoxide and methane. An example o~ such a 2 process is to pass naphtha with steam (i.e., H20/carbon mole 3 ratio o~ 1.5 to 2~0) over a nickel cataly~t at a pressure of 150 psig and an outlet gas temperature of 640C to provide a product having the ~ollowing analysis (dry basis?: methane *
34.2~, hydrogen 38~7~o~ carbon monoxide 11~8% and carbon dioxide 13.3%. The amount of methane in this process is increased by 8 ¦ passing the gaseous mixture over a second and optionally a third - 9 ¦ catalyst bed. The gases are usually cooled prior to methanation

10 ¦ to a temperature which is sufficiently low for methane synthesis

11 ¦ to occur to a substantial extent but which is not so low that

12 there is insufficient catalytic activity for reaction to proceed ¦ at an adequate rate. In general, the temperature of the 14 ¦ methanation reaction is within the range of about 200-400DC and 15 ¦ at a pressure -above that of the flrst stage, i.e. at 20-50 16 ¦ atmospheres or higher. This procedure can be used to change the -17 ¦ f-irst stage gaseous mixture to one having a final analysis 18 ~on a dry basis, and after scrubbing) o~ methane 96%, hydrogen 19 3.6~ and carbon dioxide 0.~%. Two methanation stages may be used, particularly to obtain a product having a greater percent-2} age of methane. In such a process the gas from the first stage 22 methanation is cooled prior to the second stage methanation 23 ¦ since as methane is produced the temperature o~ the gases rise~
24 I i.e., the reaction is exothermic.
25 1~ While it might be p~ssible to utilize some of this 26 ¦ technology in synthesizing methane from methanol, it shares 27 I with the above-described synthetic natural gas processes the 28 ¦ marked dis~dvantage of requiring a minimum of two reaction 29 ¦ stages to ach~eve the high methane/low hydrogen content of 30 ¦ natural gas. This, Or course, places demands on the equipment ~` _4_ 1~' . ................... . , - ,.......... ,, ,, ,, 1, .. .,~ , . . . .

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} requirements.
2 It is accordinely an obJcct of this Lnvention to provide 3 a one-step process ~or converting a methanol feed to a fuel eas containing a high proportion of methane.
A further ob~ect is to provide a process whereby synthetic 6 natural gas can be produced from methanol in a one-step catalytic 7 reaction.
B Yet another object of this invention is to provide a 9 process for converting a feed of methanol and naphtha to synthetic natural gas.
11 These and other objects will become apparent from the 12 detailed description which follows.

13 THE INVENTION A .

14 This invention is directed to the procedure for forming a fuel gas, and particularly synthetic natural gas, from methanol 16 by a one-step catalytic conversion process. The process of this invention is useful for preparing a synthetic natural gas having 18 a methane content above about 90~ as measured on a dry, carbon `
dioxide-free basis, and preferably about ~8~ or more methane, the remainder.being essentially hydrogen. (Compositions of 21 gaseous streams are stated in volume percenta~es). Other con-22 stituents are present in only small amounts; importantly, 23 carbon monoxide is essentially non-existent and the feedstoclc is 2~ completely convcrted. Thus, the gas produced is similar to or interchan~eable with natural gas and can be introduced into a `26 natural gas transmission system.
27 In the process of this invention, vaporized methanol and 28 preferably water vapor arc contact~d wlth a catalyst comprising one or more metals selected from CrouP ~III of the l'eriodic 'rable 3 particularly the platinum-group metals such as ruthenium, 1 [)768~8 .` .

1 platinum and rhodium,` on a suitable support such as a refractory 2 'oxide. The reaction is carried out at an elevated pressure and ?
3 temperature, such as 300 to 5000 psig, and 200~C to 550C, 4 preferably about 350C to 500C. The resultant gaseous mixture ; 5 comprises methane, carbon dioxide, steam, hydrogen and almost 6 no carbon monoxide. The steam and usually carbon dioxide are 7 removed from the mixture to obtain synthetic natural gas 8 The overall reaction may be depicted as follows:
9 - 4CH30H -~ 3CH4 + C02 -~ 2H20 10 This composite reaction represents the overall reaction occurring 11 within a single catalytic step.

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13 In the process of this invention, a vaporized feed 14 comprised of methanol and preferably further comprised of'water vapor is passed over a methanation catalyst. As discussed here-16 inafter,'à gaseous recycle stream may be used to provide the ` 17 water vapor and to aid in controlling the reaction temperature.
18 Wher'e the feed is obtained by vaporizin~ from the liquid state 19 or where preheat of the feed is required, the maximum preheat or vaporization temperature is limi-ted to some extent by the 21 dang-er of thermal decomposit-ion of the hydrocarbons but the 22 temperature should be sufficiently high to malntain the methanol 23 (and water where used~ in a completely vaporized state when 24 passed to the catalyst bed.
The source of the methanol feed is not critical to the 26 conversion process of this invention and the earlier described 27 natural gas and coal or other carbonaceous material reformation 28 ¦ processes provide a suitable source of methanol. However, while 29 ¦ the methano]. product streams of those processes typically contain 3o ¦ 90~ or more methanol and therefore require purification for use ' ~ ~6-¦ y tbe hem~als In~ust ~ 7fi ~ ~ ure feeds may be utll~zed ~n 2 this lnventlon.
3 The gases are contacted with the methanation catalyst 4 at a temperature sufficient to maintain the reaction at an adequate rate. These temperatures will depend largely upon the 6 particular catalyst employed, but the optimum temperatures are 7 readily determinable within the ranges disclosed herein.
8 The methanation reaction from methanol is an exothermic 9 one and operatlng conditions should be chosen to prevent the ' maximum exit temperature from exceeding 550C. The lower limit 1 for the reaction temperature is determined mainly by considera-121 tions of catalyst activity and typically is about 200C. The l3l exothermic temperature rise for a particular set of operating 14 ¦ conditions will dictate in part the entrance temperature require~

15 ¦ ments and whether recycle is necessary to maintain the reaction

16 below the 550C preferred maximum. In general it is found that

17 the lower temperatures favor the reactlon to methane subject to

18 the requirement of a vaporized feed and temperatures sufficlent tc

19 initiate reaction. Depending upon operating parameters, ~ntrance or exit conditions may be more paramount in fixing the composi-21 tion of the product gaseous mixture and are easily determinable 22 within the disclosed ranges. As such~ temperature conditions -231 favoring methanation may be more important at, say, the exit 241 and temperature control to that end via recycle, cooling, or 25l low inlet temperatures can be practiced Alternatively, low -~
26¦ temperature inlet conditions can be employed in conJunction with 27¦ the rise incident to the exothermic reaction sub~ect to the 28¦ preferred mnximum exit tempcrature of 550C. This type profile 29 ¦ will minlmize carbon deposition on the catalyst. In general, 3o it appears that the exlt conditions are more determinative of ~C~768~8 ' . , .
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1 the product mixture composition.
A preferred temperature range for this process is 3 between about 350C to 500C.
4 The weight hourly space velocity (~ISV) of the reaction 5 mixture across the catalyst bed may vary widely; it is usually 6 maintained within a range of 1 to 100, and preferably within 7 3 to 40. These values represent the amount of methanol passed 8 through the catalyst bed in terms of weight of methanol per 9 -weight of catalyst, per hour.-The pressure at which the catalytic reackion is conducted 11 is within the range of 300 psig to about 5000 psig. A preferred 12 range is between about 800 to 2500 psig and most preferably 13 from 1000 to 1500 psig. In general, the higher pressures 14 favor the conversion to-methane.
15 ¦ The catalyst utilized in the methanation process of 16 ¦ this invention comprises an active component distributed on a 17 ¦ support and should be more active than those generally used for 18 ¦ hydrocarbon reforming. The catalyst comprises one or more 19 ¦ metals selected from Group VIII of the Periodic Table.

20 ¦ Preferred among catalysts for this invention are nickel or a

21 ¦ precious metal of Group VIII, i.e. platinum, palladium,

22 ¦ ruthenium, rhodium, osmium and iridium used singly or in com-

23 ¦ bination. Ruthenium and nickel have been found very useful.

24 ¦ Other metals and metal mixtures can however be used, for example

25 ¦ cobalt alone or in mixtures similar to those in which nickel is

26 ~ used. Metals of Group I, VI and VII may also be employed

27 ¦ in admixture with the foregoing metals of Group VIII of the

28 ¦ Periodic Table.

29 ¦ The catalytic metal is normally distributed on a 3o ¦ refractory inorganic oxide suppork. Alumina is a suitable ~' I . .
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l support. In addltion, a stabili~ed alumina may be used such as 2 ceria- or thoria-stabillzed alumina. Other refractory oxide 3 supports~ such as admixtures of alumina and silica, magnesia and zirconla can be used. Generally~ highly acidic supports should `
5 ¦ be avolded to reduce problems of coke formation. The catalytic-6 ~ all~ active metal can also be supported on a zeolite material, 7 ¦ synthetic or natural, which may be mixed with other inorganic 81 oxides. Alkaline earth metal oxides can be used with one or more 9¦1 of the foregoing refractory materlals to form a thermally stable 10 ¦ mixed oxide.
ll ¦ The proportion of the catalytically active metal in the ¦
12 I catalyst composition typically depends on whether it is a base ¦
13 metal or a precious metal. Using base metals the proportion is, -~ ~
14 for example, ~rom about 3 to 80 weight %, especially 5 to 50% ~-calculated as the weight of metal oxide on the catalyst composi-16¦ tion. Using only one or more precious metals, the proportion is 171 between about 0.01 to 20~, preferably .l to 5%, calculated as 18¦ the metal on the catalyst composition Using mixtures of base anc `
l~t precious metals the amount of each, and particularly the amount `
201 o~ p~ecious metals, may be reduced. I ~ -21¦ The catalytically active metal may be incorporated with -22¦ the inorganic oxide support in accordance with methods well ;
231 known in the art for the preparation o~ methanation catalysts.
2~1 For example a catalytically active metal may be coprecipitated with a refractory insoluble compound, followed by calcination 26 to convert the coprecipitated compounds to oxides, and finall~
27 the catalyst composition is reduced to lts active state, This 28 procedure can be used wi~h nickel and aluminum salts, to which, 29, after reduction to an active state a minor proportion of an 301 o lde, hydroxlde or cerbonate of en nlkall or alkallne earth ' ' ' ' . ''~' . ',~.

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. . ' i metal is added.
2 The precious metal or its salt may be mixed with a 3 finely divided refractory supl~ort which is then suitably shaped 4 and calcined and the oxide of the metal then reduced.
The catalyst may be used in the normal type of fixed 6 bed which may be in the form of a tubular reactor or with 7 internal cooling tubes to facilitate temperature control. The 8 catalyst is in any one of the conventional forms such as 9 granules, pellets, beads, rings r cylinders, extrusions r and microspheres. Alternatively a moving bed such as a fluidized 11 bed of catalysts can be used, either with or without conventional 12 internal cooling tubes in the bed. Fluidization is maintained 13 by the passage of reactants through the bed.
14 The present conversion process does not require a feed containing water vapor in order for the reaction to proceed 16 satisfactorily, particularly at temperatures below about 350C, 17 since the reaction itself produces water. The presence of water 18 (steam) is known by the art to minimize the deposition of carbon 19 on the catalyst, thereby reducing catalyst activity, and typical processes require a molar excess of steam in the feed, g~nerally 21 2 to 3 moles per mole of methanol. While such quantities may be 22 utilized in the present process,the process of the present 23 invention xequires no water. Where water is to be present in 24 the ~eed, carbon deposition can be prevented using low steam/methanol ratios, generally on the order of 0.5 to 26 1.5 moles steam per mole of methanol. High steam/methanol ratios 27 may result in premature catalyst degradation due to sintering.
28 Thus, the ability to operate the present conversion process at low steam levels is desirable. The low steam/methanol ratio also contribues to the ability to meet the high methane ~ 768~i3 1 requirements of a synthetic natural gas in a single-step 2 conversion process. -3 The presence of the above-mentioned proportlon of water 4 vapor is preferred in the process of this invention particularly to prevent carbon deposition at the initial stages of the 6 reaction, i.e.~ prior to the formation of reaction water. As is 7 hereinafter described, the requisite water vapor can be supplied 8 by includin~ in the vaporized feed a recycled portion of the 9 product mixture exiting from the catalyst reaction zone. Water vapor-is also useful in controlllng the temperature of this 11 exothermic reaction.
12 ~The attached Figure presents a schematic illustration of 13 the process of this invention wherein a vaporized feed comprised 14 of methanol (optionally with naphtha) and water are fed to a chamber containing a catalyst which reforms the product to 16 produce a hlgh proportion Or methane. The water and carbon 17 dioxide are separated from the reformed product by conventional 18 techniques to producc a natural gas containing a minor amount 19 of hydrogen and essentially no carbon monoxide. Tne equipment requirements for this process are minimal and are significantly 21 less than that for the conventional multi-stage reactors. -22 In the Figure an experimental tubular reactor 1, is 23 shown which contains a catalyst bed 2, supporte~ in a convention-24 al manner. Methanol and water (or steam), and optiollally naphtha, are introduced into reactor 1 via line 3. Heat 26 exchanger 4 serves to vaporize the feed mixture and 27 heat it to the desired reactor inlet temperature. ~rhe 28 gaseous mixture is reformed as it passes through the 29 reactor and exits at its bottom portion~ The vaporization, and elevat:Lon in temperature~ of the methanol-water Inixture ' -11-768~8 1¦ is also, in part~ effected by the heat generated by the reaction 21 in the reactor~ and in turn~ this vaporlzatio~ assists in con-3¦ trolling the temperature in the reactor. The gaseous mlxture 41 exitsi from the reactor and passes through a cooler or condensing I means lnto water separator 5. The removal of water can be 6j¦ carried out by cooling the gaseous mixture to condense the water.
7jl In a full scale unit the high pressure of the gaseous product 8 ¦ mixture may also be used to drive a turbine to do useful work, 9 ¦ such as driving pumps to f~ed the methanol and water to the re--10 ¦ actor. The gaseous product mixture is then passed through a 11, carbon dioxide scrubber, 6, to obtain the synthetic natural gas. ' 12j A typical purification comprises passing the gases over hot 13 ! potassium carbonate to scrub out the carbon dioxide. Alterna-14 tively the pressure of the gaseous mixture in the reactor can be 15i raised sufficiently high to liquify the carbon dioxide and to 16~ facilltate its removal for use in this form. The h-igh pressure J
17' gaseous mixture which remains can then be used to drive a turbine 18 il to provide some of the energy used for accessory equipment for 19il the process. The pressure of the gaseous mixture even after its 20l use to drive turbines for accessory equipment can be sufficiently 21 Il high to feed the gases into a high pressure di~tribution system 22ll such as that for the distribution of natural gas.
23 ! In a preferred embodiment o~ this inventlon a portion 2~' of a gaseous product mixture is recycled to the reactor inlet as ;
25l1 a-component of the vaporiæed feed to control the reaction temper-~
26l ature, and to provide water vapor and hydrogen whlch extends the ~
271 catalyst life. The reactor gas is passed through a first cooling¦
28ij means 7 to r~!move heat, decreasing its temperature to a suitable j 29 !l level so that it may be recycled as stream 8 to the feed inlet. );
' 3 ~! The recycling of the reactor gas increases the water vapor con-~! -12-1~'7~80~3 1 tent in the reactor, which acts to prevent coking, By obtaining 2 the bulk o~ the water from stream ~, where the water is in vapor 3 form, additional energy is not required to vaporize water. The gases from the first cooling means are then passed through a second cooling means 9 and to the water separator 5. A second 6 recycle stream 10 also recycles the reactor gases back to the 7 reactor inlet but at a lower temperature and with a reduced water 8 content. The ratio of total recycle to the vaporized methanol 9 feed gas in stream 3 can be varied to control temperature in the catalyst. By adjusting the relative amounts of recycle gases in 11 stream 8 and 10, the opti~um amount of water can be achieved ~ while maximizing the preheat given to the fresh ~ethanol ~eed.
13 The temperature control obtained is both a function of the rela-14 tive amounts of streams 8 and 10 and their respective tempera-tures. The amount of recycle from stream 8 is typically from 16 about 25 to 100% of the total recycle gas~
17 As earlier indicated, the vaporized methanol feed may 18 further comprise naphtha. In this alternative procedure, shown 19 by the broken line in the Figure, a mixture of methanol~ water and naphtha may be fed to the reactor under the same conditions 21 described above~ In this process, when the amount of methanol 22 is substantially or significantly reduced in amount, it is 23 important to recycle to the reactor, with the feed stream, a 2 portion of the gaseous mixture to assist in the prevention of 2 carbon deposition and to effectively ut~lize the hydrogen formed 2 in the gasification reaction.
2 The vaporized methanol feed ma~, of course, contain other components capable of single-step conversion to methane.
291 When using methanol alone or in combination With a 301 naphtha feed it is preferable to ensure that the feed has a . ' '' 1.

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1 minlmum sulfur content to prevent poisonlng of the catalyst. The 2 removal of sulfur may be effected by any known process, for 3 example, by reduction of the sulfur by reducing gas to hydrogen sulfide over a metal catalyst, followed by removal of the 5 hydrogen sulfide by scrubbing. It is desirable that the sul~ur 6 content of the feedstock is below about one part per million, 7 preferably below about 0.1 part per million. The sulfur content of the feed water should also be controlled to malntain a 9- comparably low level.
The Figure, as described above schematically shows 11 small-scale equipment for carrying out the process of this 12 invention. The foregoing principles are readily applicable to 13 the design of large-scale equipment in accordance with well known }4 techniques. In particular, for tubular reactors the catalyst 15 ¦ concentration could vary vertically (with a lower eoncentration 16 ¦ at the inlet) and boiler-feed water under pre-set pressures would 17 ¦ be used to maintain control to prevent the exothermic reaction 18 ¦ for ralsing the temperature too high. The water used to cont~ol 19 ¦ the temperature is then available as a superheated high pressure 2~ ¦ steam for further use, which improves the overall economic and 21 ¦ thermal efficiency of the process. The exit gas can be used to 22 ¦ heat and vaporize the inlet feed by passing them in a convention~
23 ¦ al heat-exchange arrangement.
24 The following examples further illustrate this invention.
EXAMPLE I
26 In this run, the catalyst comprised 0.5~ ruthenium on 27 alumina pellets (14-20 mesh) prepared according to conventional 28 procedures. A methanol/water mixture comprising one mole of 29 methanol for each 0.5 moles of water was fed to a preheater and 3 vaporized. rrhis feed mixture was passed over the ca~alyst at ~` -14~

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~ '7~808 1 ~400DC inlet tempelature and 1100 psig. About 5 cc. of catalyst 2 ¦ was employed. The results of this run are summarized in the 3 ¦ following table.
4 ¦ TABLE I
5 I Product Composition, Vol. %
6 ¦ Run Duration (hrs.~ (Dry BasisL _ 7 ~ C~ C02 H2 Other 8 4 71.0 22.8 3.3 Balance -9 ¦ 51 71.0 23.0 3.4 Balance 10 ~ Carbon monoxide was not detected in the product 11 ¦ composition. The balance materials were believed to be hydro-12 ¦ carbons and/or air. Conversion of the methanol was approximately 13 ¦ 100~ and no ethers were detected.
14 ¦ EXAMPLE II
15 ¦ The catalyst for these runs was 7.5 cc of 14-20 mesh 16 ¦ 0.5~ ruthenium on alumina. This~was diluted with 242.5 cc of 17 ¦ alpha alumina, charged to a tubular reactor and reduced at 500C
18 ¦ for 4 hours with hydrogen. After reduction of the catalyst~ the 19 ¦ temperature was lowered to 400~C and the reactor was pressurized 20 ¦ with hydrogen to the desired operating pressure. The mole 21 ¦ ratio of steam to methanol was 1.5:1, the feed rate was 14 cc 22 ¦ methanol/hour/cc catalyst, and the reactor inlet temperature 24 ; wes 400~C. esult6 are give~ }n the following table.

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2 ¦ Run Product Composition l DurationPressure Volume %
31 _ (hrs.)(psig) _ (dry basis) 41 CH4 ~ CO H2 Other 51 2 300 50.0 23,5 0.2 20.2 6.1 6 ¦ 10 500 62.0 21.8 trace 11.2 5.0 ; 71 13 1100 68.5 24.0 N.D 5.0 2.5 ¦ ~ 1600 70.0 23.5 N.D, 4.3 2.2 9 ¦ As indicated, carbon monoxide was essentially non-existant in 10 I these runs. Conversion of methanol was about 100~ and no ethers 11 ¦ were detected. The compounds designated as "other" were believed 12 ¦ to be hydrocarbons and/or air.
13 ¦ EXAMPLE III
14 ¦ 7.5 cc of 14-20 mesh 60% nickel on alumina was diluted 15 ¦ with 242.5 cc of alpha alumina and reduced at 500C for 6 hours 16 ¦ with hydrogen. At 400C and 1100 psig, vapori2ed methanol and 17 ¦ water (1~5 moles steam per mole methanol) was passed over the 18 ¦ catalyst at the aame rate as in Example II. After 135 hours, 19 ¦ methanol had yet to appear in the product mixture. The product 20 ¦ composition was on a volume, dry basis: 69% CH4, 22.7% C02, 21¦ 0~ CO, 5.3% H2 and 3.0~ other materials.
22 ¦- The gas mixtures shown can be used directly as fuel 23 gases or are converted to a high quality synthetic natural gas 24 ¦ upon removing the carbon dioxide. As these runs show, the 25 ¦ process of this invention produces a synthetic natural gas 3 26 ¦ consisting essen~ially of methane with re-latively m~nor amounts 27 ¦ of hydrogen and little or no detectable amounts of carbon 28 ¦ monoxide. The synthetic natural gas has a heating value of 29 ¦ about 1000 BTU/ft.3. The hydrogen content in the final product 3 ¦ is preferable maintained below about 5~ and advantageously .~.,',.~' . I .

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2 high flame speed and a too rapid burnine of the gas~ Carbon .
3 monoxide in the gas presents a safety hazard and ls indicative ..
4 of inefficiency i.n the conversion reaction.
This invention has been described in terms of specific 6 embodiments set fnrth in detail. .Alternative embodiments will 7 be apparent to those skilled in the art in view of this disclosur .
8 and accordingly such modifications are to be contemplated within 9 the spirit of the invention as disclosed and claimed herein, .-~

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Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A single-stage catalytic process for the production of a fuel gas from methanol in the presence of a catalyst comprising a Group VIII metal on a refractory inorganic oxide support charac-terized by passing a gaseous feed mixture of methanol and steam containing from 0.5 to 1.5 moles steam for each mole of methanol into contact with said catalyst at a pressure in the range of from about 800 psig to about 1600 psig and a temperature in the range of from about 350°C to about 500°C while maintaining said gaseous feed in a completely vaporized state whereby said gaseous feed is reformed entirely in the vapor phase to a gaseous product mixture containing at least about 90% methane by volume on a dry, carbon dioxide-free basis.

2. The process of claim 1 wherein said catalyst is selected from the group consisting of nickel, platinum, palladium, rhodium, ruthenium and mixtures thereof on a refractory inorganic oxide support.

3. The process of claim 2 wherein said catalyst comprises ruthenium.

4. The process of claim 2 wherein said catalyst comprises nickel.

5. The process of claim 1 wherein said gaseous feed contains at least a portion of said gaseous product mixture recycled thereto.

6. The process of claim 1 wherein said temperature is in the range of from about 380°C to about 420°C.

7. The process of claim 1 wherein said pressure is in the range of from about 1100 psig to about 1600 psig.